This invention relates to a constant velocity joint, particularly to a constant velocity joint providing for substantial angular and axial displacement of the rotative bodies, as for example may be used in a front wheel drive vehicle.
In front wheel drive vehicles, the drive shaft extends laterally from the transmission to the wheels, and must provide for angular movement with respect to the transmission as the wheels move up and down in a vertical plane. Since the wheels do not move in a radius about the connection of the drive shaft to the transmission, the length of the shaft must be able to change and thus provision must be made for axial movement. Normally constant velocity joints used in such high torque applications are made of heat treated steel forgings which require substantial amounts of difficult machining to obtain circular or elliptical surfaces and must be made to close tolerances. These joints are very expensive to make and for their size are very heavy and add weight to the vehicle. Efforts have been made to reduce the cost of making universal joints as indicated by the design in U.S. Pat. No. 3,815,381 which shows a cage made of a die formed cylinder of heavy wall construction. However, considerable machining is still required and such joints do not have reduced weight. Joints presently available use a plurality of balls slidable in channels in either an inner and/or outer cage member for transmitting torque. Such a joint is shown in U.S. Pat. No. 1,533,425. These joints are subject to substantial wear at the interface between the balls and channels since torque is transmitted there. The balls also serve, however, as centering devices to maintain alignment between input and output shafts. Thus, as wear proceeds, there can be substantial play between the parts which increases the possibility of further wear and actual separation and failure of the joint. Another disadvantage is that the angle of articulation of such joints is limited due to the plurality of balls and the size of the cage housing them. Means other than the ball in channel type have been tried for transmitting torque, e.g., as shown in U.S. Pat. No. 3,406,534 and U.S. Pat. No. 3,903,711. In U.S. Pat. No. 3,406,534 Chapper, the joint provides for angular and axial movement of the shafts but the axial movement is crude in that one of the shafts itself is simply slidable in the coupling. This is obviously satisfactory for a toy but not for use in a larger vehicle. The joint of U.S. Pat. No. 3,903,711 provides solely for angular movement and not axial movement.
Thus, it is an object of this invention to provide a constant velocity joint which provides for both axial and angular displacement with a minimum amount of wear, is easy and inexpensive to fabricate and of light weight.
It is also an object of this invention to provide a constant velocity joint which provides for substantial angular and axial displacement and has separate means for transmitting torque and maintaining alignment of the apparatus.